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• Watershed Management Plan Background • The ʻ Ewa District AGENDA • ʻ Ewa Water Demand and Sources: Existing (2010) • ʻ Ewa Water Demand and Sources: Future (2035) • Watershed Management Projects and Strategies • WMP Approvals Process ʻ EWA WATERSHED MANAGEMENT PLAN COMMUNITY MEETING #3 September 12, 2017 2
WATERSHED MANAGEMENT PLAN BACKGROUND ʻ EWA WATERSHED MANAGEMENT PLAN COMMUNITY MEETING #3 September 12, 2017 3 3
Planning Framework O ʻ ahu General O ʻ ahu General • Act 152: Watershed Protection • Act 152: Watershed Protection State Water Code State Water Code Plan Plan • Wai ā hole Ditch Decision • Wai ā hole Ditch Decision • Ch 30, ROH Water Management • Ch 30, ROH Water Management • BWS Sustainability Mission • BWS Sustainability Mission Hawaii Water Plan Hawaii Water Plan • State Water Projects Plan • State Water Projects Plan 8 DP/SCP 8 DP/SCP • Agricultural Water Use and Development Plan • Agricultural Water Use and Development Plan Land Use Land Use • Water Quality Plan • Water Quality Plan Plans Plans • Water Resource Protection Plan • Water Resource Protection Plan • County Water Use and Development Plans • County Water Use and Development Plans O ʻ ahu Water O ʻ ahu Water Management Plan Management Plan 8 Watershed Management Plans 8 Watershed Management Plans By DP/SCP District By DP/SCP District Ko ʻ olau Ko ʻ olau Ko ʻ olau Ko ʻ olau North North Central Central East East ʻ Ewa ʻ Ewa Wai ʻ anae Wai ʻ anae PUC PUC Loa Loa Poko Poko Shore Shore O ʻ ahu O ʻ ahu Honolulu Honolulu September 12, 2017 4 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 • County “ Water Use and Development Plans ” are required by the State Water Code • “ O ʻ ahu Water Management Plan ” is required by Revised Ordinances of Honolulu Chapter 30 • Honolulu Plans are district specific and called “Watershed Management Plans” (WMPs). District ‐ level water and land use plans allow for community ‐ specific actions and strategies • Guidance is provided by the Hawai ʻ i Water Plan and the City’s ʻ Ewa Development Plan . • WMPs require approval by BWS, DPP, City Council, and CWRM 4
Watershed Management Plan Goal To formulate an environmentally holistic , community based , and economically viable watershed management plan that will provide a balance between: 1. The protection, preservation, and management of O ʻ ahu’s watersheds 2. Sustainable ground and surface water use and development to serve present users and future generations. September 12, 2017 5 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 The WMP Goal applies to all of the Districts 5
Watershed Management Plan Objectives 1. Promote sustainable watersheds; 2. Protect and enhance water quality and quantity; 3. Protect Native Hawaiian rights and traditional and customary practices; 4. Facilitate public participation, education, and project implementation; and 5. Meet future water demands at reasonable costs. September 12, 2017 6 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 The WMP Objectives apply to all of the Districts 6
ʻ Ewa WMP Table of Contents Chapters Executive Summary 1. O ʻ ahu Water Management Plan Overview 2. ʻ Ewa Watershed Profile 3. Water Use and Projected Demand 4. Plan Objectives and Water Supply, and Watershed Management Projects and Strategies 5. Implementation Appendices A. O ʻ ahu Watershed Management Plan Framework B. Plans, Policies, Guidelines, and Controls C. O ʻ ahu Water Use Permit Index D. Overview of O ʻ ahu Hydrogeology September 12, 2017 7 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3
(2009) THE ʻ EWA DISTRICT (2016) (2009) (in progress) (2012) (in progress) (in progress) (FY ‘18) ʻ EWA WATERSHED MANAGEMENT PLAN COMMUNITY MEETING #3 September 12, 2017 8 Size: 33,677 acres (52.6 square miles) almost 1/10 of O ʻ ahu 8
Hydrology and Water Sources Precipitation Percolation Northeast Trades Transpiration Spring Perched Water Streams Evaporation SEA LEVEL Spring Spring Dike Confined Freshwater Water CAPROCK Aquifer Salt Water Salt Water September 12, 2017 9 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 9
Hydrology and Water Sources Rainfall Rainfall Brackish Water Lens Salt Water Leakage from the basal aquifer to the caprock aquifer • Impermeable caprock holds the fresh basal water inland. • Caprock also holds water from rainfall and leakage from the basal aquifer in its limestone layers September 12, 2017 10 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 In Ewa, there is a special geologic formation called “caprock.” • The coastal plain is made up of sediments that form a relatively impermeable sedimentary material, or “caprock.” • The caprock restricts the seaward flow of fresh ground water. • Caprock also holds water within its limestone layers. This water is fed by rainfall and leakage from the basal aquifer. • Irrigation from sugar plantations used to enhance the caprock aquifer, but since the closing of Oahu Sugar Company (OSCo), the brackish caprock lens shrank. 10
Climate • Low rainfall • Average annual rainfall in ʻ Ewa = 20” - 40” • Average annual rainfall on O ʻ ahu = 20” – 300” • Average annual rainfall for the State = 10” – 440” • Within the district, rainfall decreases when going mauka to makai • Average temperatures: 60 ˚ to 91 ˚ September 12, 2017 11 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3
Climate Change Rainfall: Dry areas will get drier by 2100 Source: Figure developed by Abby Frazier, UH. Modified from data presented in Helweg et al. 2016 September 12, 2017 12 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 Past • Air temperature is increasing(0.3 o F/decade over the past 30 years) 1 • Rainfall has decreased by ‐ 15% over the past 20 years • Rainstorm intensity has increased (+12%, 1958 ‐ 2007) 1 Future • There will be less rainfall by 2100 in leeward areas in both wet and dry seasons. • Rainfall in the Ko ʻ olau Mountains, especially in the Honolulu area, will increase in the wet season. • Implication: Leeward sources will deplete and more water will need to be transported from the Pearl Harbor aquifer. • ʻ Ewa will need to diversify it’s water sources, conserva � on, recycled water and limited desalination. 12
ʻ Ewa’s Sugar History September 12, 2017 13 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 • 1897, Oahu Sugar Company established on the ʻ Ewa Plains • 1925, 50,000 tons of sugar produced by ʻ Ewa Sugar Planta � on • Sugar is a very thirsty crop, consuming 6,700 gpad (2004 WUDP) or 1,400 ‐ 5,000 gad (IWREDSS duty), compared with 3,400 gpad for diversified ag in relatively dry areas • By the 1930s, ʻ Ewa Planta � on, O ʻ ahu Sugar Company, Honolulu Planta � on = over 200 mgd from Pearl Harbor Aquifer to irrigate sugar on the ʻ Ewa Plains. (source: Sugar Water, p. 108) • 1939 ‐ 1944, ~3,000 acres converted to military use • 1970 Oahu Sugar Company acquired ʻ Ewa Planta � on • 1988 OSCo Map of sugar lands; 13, 536 acres (out of 33,677 acres in ʻ Ewa) • 1990, OSCo produced 76,925 tons of sugar on 11,526 cul � vated acres ( ʻ Ewa and Central), yielding 13.66 tons per acre. • 1995, OSCo harvested last crop 13
Full Buildout of Master Plans September 12, 2017 14 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 As sugar has declined, it has been replaced with many different land uses: • Resort • Industrial • Residential • Agriculture • Military • Kalaeloa There are master plans for the development of most of ʻ Ewa 14
ʻ Ewa Population: 1980-2010 120000 Resident Population 100000 80000 60000 40000 20000 0 1980 1990 2000 2010 Change Percent 1980 1990 2000 2010 (1980 ‐ 2010) Change ʻ Ewa DP Area 35,709 42,983 68,696 101,397 65,688 184% O ʻ ahu Total 762,564 836,231 876,156 953,207 193,211 25% % of O ʻ ahu 5% 5% 8% 11% September 12, 2017 15 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 • Over the past 30 years (1980 – 2010), ʻ Ewa popula � on increased 184% • It’s share of the total O ʻ ahu popula � on increased from 5% to 11% 15
ʻ Ewa Projected Population: 2010 - 2035 200,000 Resident Population 150,000 100,000 50,000 0 2010 2035 Change Percent 2010 2035 (2010 ‐ 2035) Change ʻ Ewa DP Area 101,397 173,846 72,449 71% O ʻ ahu Total 953,207 1,071,225 118,017 12% % of O ʻ ahu 11% 16% September 12, 2017 16 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 • Over the next 25 years, the ʻ Ewa popula � on is expected to grow by 71% and increase its share of the total O ʻ ahu popula � on from 11% to 16% 16
Issues and Questions Raised • Non-BWS water systems need to be accounted for • What are the flooding issues? • What is the state of the BWS water system in ʻ Ewa? • Is our drinking water safe? • Desalinated water: what will it be used for? • Is there enough water for planned development? • Protect traditional and customary practices • Education and community engagement is important • Land use and water planning needs to be integrated September 12, 2017 17 ʻ EWA WATERSHED MANAGEMENT PLAN – COMMUNITY MEETING #3 Issues raised in interviews and in previous community meetings 17
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